Micro-wave discharge tube



Nov. 26, 1957 MASAMICHI KENMOKU 2,814,756

MICRO-WAVE DISCHARGE TUBE Filed Nov. 14, 1955 Inventor Attorney United States 2,814,756 MICRO-WAVE DISCHARGE TUBE Masamichi Kenmoku, Minato-ku, Tokyo, Japan, assignor to International Standard Electric Corporation, New York, N. Y., a corporation of Delaware Application November 14, 1955, Serial No. 546,647 Claims priority, application Japan January 14, 1955 7 Claims. (Cl. 315'3.6)

Micro-wave discharge tubes which perform amplification or oscillation by the interaction of a wave in a retardation circuit and anelectronbeam'emitted from an electron beam source, are exemplified by traveling wave tubes or a backward wave tube etc. up to this time. I I

The present invention offers a micro-wave discharge tube using those principles but provided with a new operating system.

The invention and its manner of operation will be best understood by the description made in connection with the drawings in which:

Figs. 1, 1A and 2 are diagrammmatic representations of the elements of micro-wave discharge tubes illustrating several modifications of the invention.

Figs. 1 and 1A show a practical configuration sketch of the most simple case of this invention wherein a retardation circuit is divided into two parts represented by helices. In these figures 1 is an electron beam source from which the electron beam is to be emitted; 2 is an electron beam; the electron beam 2 reaches the collector electrode 3 after passing from X to Y on the axis XY; 4 and 5 are the retardation circuits represented by helices and are positioned to interact with the electron beam 2. The helices 4 and 5 may be regarded as one helix divided into two units as shown in the drawing. These elements are all enclosed in an evacuated envelope, as indicated at 25.

The ends 22 and 19, of helices which face each other at the dividing area are not connected for high frequency direct transmission. In Fig. 1 the end 19 of helix 5 is connected to the ends of helix 4 by conductor 9. The end 21 of the helix 5 and the end 22 of the helix 4 are connected respectively to input and output leads 14 and 13. It will be clear that either 13 or 14 may be used as input leads or output leads. A high Q filter 15 may be used in line 9 if desired.

The end 22 of the helix 4 is connected to the end 21 of the helix 5. The end 19 of helix 5 and the end 22 of helix 4 are connected to input and output leads 14 and 13 respectively.

The operation of such a discharge tube will now be explained. Starting first with Fig. 1, it may be assumed that a wave input is effected over line 14 so that the Wave will traverse the helix 5 in the same direction as the electron beam travels. Thus, this helix 5 will operate as a normal traveling wave amplifier. This amplified energy may then be applied over line 9 and through the filter 15 if desired to the input end 20 of helix 4. Except for helix 4 the normal amplified output energy would then appear in output lead 13. However, the electron beam which has already been velocity modulated in traveling through the helix 5, passes through helix 4 tending to induce in this helix a wave of the same frequency as that applied at end 20. If the phase relation of the wave induced in helix 4 is properly controlled it will tend to augment the output at the lead 13. It will 2 be seen that helix '4 operates in the manner of the backward wave amplifier except that the electron beam has already been modulated by the amplification action in helix 5.

Accordingly, there may be an amplification of this bunching elfect so that there is produced at end 20 energy in the helix a wave of opposite phase to that being applied which may produce essentially a negative feedback action within the tube. In this case there may be produced the higher negative admittance characteristic common to negative feedback amplifier arrangements. Although lead 9 has been shown as a lead conductor there may be a capacitive coupling applied, for instance in circuit 15, so that helices 4 and 5 may be operated at difierent D. C. potentials if desired. In addition, a shielding plate may be introduced between ends 19 and 22 so as to prevent any'fe'edback coupling directly between helices 4 and 5. It will also be clear that by feeding back energy excessively from output lead 13 to input lead 14 the conventional oscillator structure may be provided. v

.In addition, it will be recognized from a knowledge ofthe backward wave theory that the desired amplification or negative feedback control can be adjusted by choosing the proper axial length for the helix 4. Furthermore, the action of this negative feedback portion can be controlled by varying the velocity of the electron beam.

The various other features commonly used in traveling wave tubes may be applied, such as attenuating devices applied to the helices for stabilising the performance of the tube. Also the conventional chokes and the like may be provided at input and output leads 14 and 13. It will also be apparent that various types of retardation circuits may be used, and suitable sizes and shapes thereof may be provided as in conventional traveling wave and backward wave amplifier circuits. Fig. 1A is similar to the structure shown in Fig. 1 except that here the lead 14 is applied at the end 19 to helix 5 so that the initial portion of the system serves as a backward wave amplifier. End 21 of helix 5 is then interconnected by lead 19 and filter 15 to end 22 of helix 4 so that this second helix serves now as a normal traveling wave amplifier. In this arrangement then the initial portion of the tube may operate in accordance with the principles of regeneration known to backward wave amplifiers. The second helix 4 then serving as a conventional traveling wave amplifier structure.

It will be recognized then that if in Figs. 1 and 1A input is applied at lead 13 and output taken from lead 14, the tubes will each operate substantially as described except that now the input energy will first be applied to the end of the beam adjacent the collector electrode Y. This connection is probably less desirable than that first described as it introduces the energy at the end of the beam which has already been somewhat weakened by the interaction of the beam with coils near to the electron gun electrode.

Fig. 2 illustrates an example of traveling wave tubes similar to the illustration of Fig. 1 except that here instead of two portions of the helices 4 and 5 there are included additional helix portions 6, 7 and 8. These portions are interconnected by high frequency leads 10, 11 and 12 and may each be provided with loading filters 16, 17 and 18. Thus there can be effected alternate forward and backward wave type of retardation line sections. The number of such lines used may be shown either odd or even. In the example shown for illustration there are five such retardation circuits employed.

The operation of the system in accordance with Fig. 2 is essentially the same as the operation explained in connection with Fig. 1. However, because of the larger r 1C6 Patented Nov. 26, 1957 numbers of coils and different combinations provided greater flexibility in operation may be achieved.

It will be appreciated that in accordance with the present invention terminal leads may be brought out externally of the tube envelope for making and the interconnections between the various helices may then be made externally of the tube structure, thus any of the various desired operational circuits may be used with the tube.

It will be clear that many other modifications and alterations of thetube structure in accordance with the principles of this invention may be applied without departing from the scope of the invention as outlined in the appended claims. 1

What is claimed is:

1. An electron discharge device comprising an electron beam source, a collector electrode, a plurality of separate retardation wave transmission means positioned axially with respect to each other and adjacent said beam to provide energy interaction between a wave in said retardation transmission means and said electron beam, characterized by wave transmission coupling means interconnecting correspondingly positioned ends of said wave retardation means for series transmission of wave energy and wave input and output means coupled to the other ends of said wave retardation means, respectively.

2. An electron discharge device according to claim 1, wherein said corresponding ends are the ends nearest said electron beam source.

3. An electron discharge device according to claim 1, wherein said corresponding ends are the ends adjacent said collector electrode.

4. An electron discharge device according to claim 1, further characterized by a tuned filter in said coupling means.

5. An electron discharge'device according to claim 1, wherein said separate retardation means consists of two wave transmission means.

6. An electron discharge device according to claim 1, wherein there are provided more than two axially aligned retardation means, characterized in that said coupler means are provided between one end of each of the end retardation means and the next adjacent of the intermediate retardation' means, and between both corresponding ends of the intermediate retardation means.

7. An electron discharge device according to claim 6, further comprising filter means in each of said coupling means.

References Cited in the file of this patent UNITED STATES PATENTS 

